The present invention relates in general to an apparatus and method for mixing and injecting an urethane blend which forms a urethane foam and more particularly to an apparatus which is capable of repeatedly mixing, delivering, and injecting a preprogrammed amount of the urethane blend with minimal cleaning and clogging concerns. The present invention represents both a system for optimum delivery of the urethane blend and a unique mixing head which is used as a part of the system. It is capable of mixing and delivering a preprogrammed quantity of urethane in a very short period of time.
Urethane foam is a common compound which is often used to fill and seal gaps and holes within a structure and also provide added structural integrity within said gaps and holes. It has found wide use within the industrial, residential, and commercial sectors. It is also available in small canisters at most home supply stores. One of the many industrial uses for urethane foam includes the filling of holes or cavities in railroad ties. Railroad ties often contain holes which are formed from removed railroad spikes. A hole in a railroad tie allows entry of water and other materials which can serve to deteriorate the structural integrity of the tie. If filled with a material which expands to fit and seal the hole or cavity, and which further is capable of contracting, expanding, and moving with the tie, the hole or cavity remains sealed and the internal structure of the tie is protected from external elements. The art of the present invention is capable of precisely mixing and repeatedly delivering the components of urethane foam in a preprogrammed amount and is especially adapted for delivering the mixed foam into spike holes or cavities within railroad ties.
As intimated, urethane foam is formed when an urethane blend is mixed with a high molecular weight alcohol. That is, when a 4,4-diphenylmethane (MDI) compound (or equivalent) is thoroughly mixed with a polyol, typically a polyhydric alcohol containing three or more hydroxyl groups (or equivalent), an exothermic reaction occurs which forms a thermosetting urethane foam. To date, attempts at mixing and delivering preprogrammed amounts of a urethane foam have been fraught with problems. Prior to the art of the present invention, the mixing and delivering devices had a minimal amount of control over the quantity of urethane foam delivered. The user could not be assured that the same preprogrammed amount of urethane could or would be delivered for every shot or use of the device. Further problems of the prior art included clogging or premature curing of the mixture within the mixing head. That is, if the urethane hardens within the mixing head it often clogs the head and prevents delivery of the mixture. This is especially true when one of the constituent compounds bleeds into the supply line or valve for the other compound. An even further prior art problem includes the excessive amount of time which was necessary to deliver a preprogrammed amount of urethane. Ideally, the urethane mixture should be delivered instantaneously.
The present art overcomes the aforementioned prior art limitations by providing an apparatus, system, and method for mixing, delivering, and injecting a preprogrammed and repeatable amount of urethane in a short period of time without clogging or premature curing of the urethane mixture within the mixing head which delivers the urethane. The preferred embodiment of the present art utilizes uniquely heated storage and feed tanks for reducing the viscosity and improving cure time of the urethane constituents and a unique pump assembly to assure quick and repeatable delivery of the constituent compounds.
Accordingly, it is an object of the present invention to provide a method, system, and device for optimally mixing and injecting a two part urethane foam which is capable of delivering a repeatable and programmed amount of urethane foam into a hole or cavity.
Another object of the present invention is to provide a method, system, and device for optimally mixing and injecting a two part urethane foam which does not exhibit mixing head clogging when properly used.
Another object of the present invention is to provide a method, system, and apparatus for optimally mixing and injecting a urethane which is capable of mobility on railroad tracks and on railroad ties when a rail has been removed.
A further object of the present invention is to provide a method, system, and device for optimally mixing and injecting a two part urethane foam which delivers the urethane quickly.
A still further object of the present invention is to provide a new and improved mixing head as an integral part of the present art apparatus which provides the aforementioned advantages and is designed to work in conjunction with the present art apparatus.
A yet further object of the present invention is to provide a pump mechanism capable of continuous pumping action in both extension and reflex for precise mixture control.